"The continued economic slowdown in the United States has adversely affected advertising revenues across the company's businesses, primarily at the local level, and the effects of the current financial crisis are likely to cause further declines in advertising spending," CBS Corp. said in a statement.

It now predicts full-year 2008 adjusted operating income before depreciation and amortization to fall in the mid-teen percentage range. Previously, it had targeted a gain in the low single digits.

After preliminary checks, it expects to incur a non-cash impairment charge of about $14 billion in the third quarter to write down the value it attributes to goodwill, FCC licenses and certain investments.

For that quarter, CBS Corp. expects earnings per share to fall, but revenue to rise 3%.

In its earnings warning, Viacom said its third quarter performance was hurt by a decline of approximately 2% in worldwide ad revenue, driven by a 3% drop in the U.S. Its international business was up approximately 8% though, it said.

In the second quarter, Viacom's networks had already reported a mere 1% domestic ad revenue gain.

"Given the rapid softening of the economy and the uncertainty this creates in forecasting advertising growth, we are taking the prudent step of moderating our near-term targets," said Viacom president and CEO Philippe Dauman.

Morris made his most significant reductions to his advertising, DVD, theme parks and consumer products business outlooks.

For example, he expects a 6% decline in total major media advertising spending in 2009 led by broadcasting and print. Among others, he calls for a 1.9% decline in cable network advertising, the first such decline on record.

Despite the current market challenges, Morris expects the media sector "should regain its premium to the S&P 500" eventually "as there have been no systemic changes brought on by the current economic crisis."